Regarding a semiconductor integrated circuit including a metal-oxide-semiconductor (MOS) field-effect transistor (FET), there has been a problem of random telegraph signal noise (hereinafter, referred to as “RTS noise”) caused in the MOSFET. As a semiconductor integrated circuit including a MOS field-effect transistor, for example, a complementary metal oxide semiconductor (CMOS) solid-state image sensor is known. More specifically, a MOS field-effect transistor is used in a comparator that composes an AD conversion unit in a CMOS solid-state image sensor including a column-parallel AD conversion unit for performing, for every pixel column, an AD conversion of an analog pixel signal read from a pixel, for example (see Patent Document 1 for example).
As a reference index for indicating a level of an image quality of a CMOS solid-state image sensor, there is temporal flickering in a sensed image. The temporal flickering in an image is caused by temporal and random changes in a signal level detected from each pixel. As one of the reasons, for example, it has been known that, in a case where an RTS noise is generated in a MOS field-effect transistor used in the comparator composing an AD conversion unit, this causes remarkable flickering in a sensed image. To reduce this flickering in the image, it is needed to reduce the RTS noise generated in the MOS field-effect transistor, which is a cause of the noise.
To reduce the RTS noise generated in the MOS field-effect transistor, conventionally, there has been a method for composing the MOSFET, which may be a cause of the noise in the semiconductor integrated circuit, with a MOS field-effect transistor of an embedded channel type (see Patent Document 2, for example).